This invention relates to methods and apparatus for segregating materials from a common source for different applications. More particularly, it relates to methods and apparatus for segregating pond coal combustion materials.
Coal fired electric power plants use holding ponds for the byproducts of coal combustion. These ponded materials can contain many types of minerals and other materials, including ash, carbon, pyrites and magnetics. It is environmentally desirable to use these ponded materials rather than treat or handle them as waste. In order for this ponded coal combustion material to be converted to useful construction materials, the materials must be segregated, and certain parts of the materials, such as pyrites, magnetics and carbon must be removed therefrom.
It is, therefore, one object of this invention to provide an improved method for segregating ponded coal combustion materials.
It is another object of this invention to provide a method for segregating ponded coal combustion materials into materials which are suitable for block sand products, concrete or mid-size sand products and fine ash products.
In accordance with one form of this invention there is provided a method for segregating ponded coal combustion materials.
The materials are first removed from the pond. The materials are fed to a screening system, thereby segregating a first size material from the remainder of the materials. Preferably, a magnetic separator removes the iron bearing materials from the remainder of the materials. The remainder of the materials are fed to a hydraulic classifier apparatus. A coarse material is discharged from a first output of the hydraulic classifier apparatus, and a middling size material is discharged from a second output of the hydraulic classifier apparatus.
The middling size material is segregated by low, middle and high specific gravities. Preferably, the low specific gravity middling material is fed to a sizing sleeve where coarse low specific gravity middling material is segregated. Also, preferably, the coarse low specific gravity middling material is combined with middle specific gravity middling material, and after de-watering, forms a concrete or mid-size sand product. Also, preferably, the coarse materials from the hydraulic classifier is combined with the first size material, and after de-watering, forms a block sand product.